Greenpeace marked Earth Day by installing six wind neon-green turbines on the Michigan Avenue Bridge downtown, but its statement in support of wind power was short-lived.

The windmills that Greenpeace put on the bridge damaged railings that were just restored, and could have hurt someone, the city said. That someone could have gotten hurt is a little hard to believe, in that they weren't spinning, and they were about 15 feet above the heads of anyone walking by.

Claiming that the group did not have a permit for the display, police ushered the peaceful demonstrators off the bridge in fairly short order.

The display was meant "to underscore the crucial role wind must play in cutting global warming pollution, creating millions of jobs, and providing energy independence for all Americans," according to a release from the group.

Chicago police ordered the activists to take down the 25-foot poles, which were fastened with metal bolts to the railing of the newly refurbished bridge. The Michigan Avenue bridge rehab was a $3.5 million project.

Crain's reported that one of the responding officers said city workers would inspect the bridge and bill Greenpeace for any damage.

Each demonstrator was issued a citation for gathering without an appropriate permit.